Regenerator seal with cross arm



March 28, 1967 W l, CHAPMAN ET AL 3,311,162

REGENERATOR SEAL WITH CROSS ARM Y TEX l INVENTOR WIJ/Liam Mpman Lyj'Jrnes H. Jh/'t field BY Clinton Ptwood Xml/'am l?. Ziewke Jr.

March 28, 1967 W 1 CHAPMAN ET AL 3,311,162

REGENERATOR SEAL WITH CROSS ARM Filed 061;. 7, 1965 4 Sheets-Sheet 2INVENTOR.

william l Chapi-:an

BY `Limes H. Z/hitfiezd i fray/V594?.

March 28, 1967 W, CHAPMAN ET AL 3,311,162

REGENERATOR SEAL WITH cRoss ARM 4 Sheets-Sheet 5 Filed Oct. '7, 1965 ,9'fray/VIK? IIIlllllrlvllullllll'.llllllnnlllllll'lllllllllnllifrllrlllMarch 28, 1967 w, CHAPMAN ET AL 3,311,162

REGENERATOR SEAL WITH CROSS ARM Filed Oct. 7, 1963 4 Sheets-Sheet 4 49f/ ffii; /A M j INVENTOR. 4,? win/'arl l. Chapman william H. Zien/ 6 Jr:

United States Patent O 3,311,162 REGENERATOR SEAL WITH CROSS ARM WilliamI. Chapman, Birmingham, James H. Whitfield,

Madison Heights, Clinton P. Atwood, Warren, and

William A. Ziemke, Jr., Livonia, Mich., assignors to ChryslerCorporation, Highland Park, Mich., a corporation of Delaware Filed Oct.7, 1963, Ser. No. 314,467 21 Claims. (Cl. 165-9) This invention relatesto improvements in a seal for the rotating surface of a regenerator of agas turbine engine.

In one type of 'gas turbine engine, a counter flow disk type regeneratorrotatable about its axis and comprising a multitude of axial gasIpassages extending between parallel axially opposed plane end surfaceshas one sector of its surface in the path of comparatively hotlow-pressure gases to be heated thereby and a second sector of saidsurface in an oppositely directed path of comparatively coolhigh-pressure inlet gases to preheat the latter upon rotation of theregenerator to bring its heated sector into the path of the cooler inletgases. In consequence of rotation of the regenerator and its alternateheating and cooling resulting from the counter fiowing hot and coolgases flowing through the separate sectors, the regenerator is subjectto continual warping such that the provision of an efiicient sealbetween the hot and cool gases at the juncture of their paths with theregenerator end surfaces has not been possible heretofore. Reference isalso made to copending application Serial No. 314,441, filed on the dateof this application, now Patent No. 3,234,999 for further detailsrelating to the type of structure with which the present invention isconcerned.

An important object of the present invention has therefore been toprovide an efficient seal between the conduits for the inlet and exhaustgases at the end surfaces of a regenerator for a gas turbine enginewhich maintains sliding and sealing contact with the continually warpingsurfaces of the regenerator without subjecting the seal to unduepressure and excessive wearing of the sealing parts in consequence offrictional drag.

Another and more specific object has been to provide such a sealcomprising an arcuate flexible rubbing seal having an innersealingsurface in sliding and sealing contact with a plane axial end surface ofthe regenerator along the circumference of one of said sectors. Anarcuate base plate confronts and is spaced from the outer side of therubbing seal opposite the latters innersealing surface to enable freedomof flexing or axial movement of the various parts of the rubbing seal asrequired to conform closely to the plane end surface of the regeneratorregardless of the latters warping or thermal distortion. An arcuatebridge structure coaxial with the rubbing seal and base plate hasconcave and convex edges pivotally engaging the base plate and the outerside of the rubbing seal respectively. The bridge structure extendsradially from its concave edge to its convex edge in the directiontoward the high pressure side of the seal. An arcuate fiexible resilientdiaphragm type seal engages the outer side of the rubbing seal in fluidtight contact along the length of the seal and extends radially from itsengage- -ment with the rubbing seal and along the bridge in thedirection toward the low presure side of the seal to the concave edge-of the lbridge so as to overlap the juncture between the convex edge ofthe bridge and the rubbing seal. An edge of the base plate is formedclosely around 3,311,162 Patented Mar. 28, 1967 ICC the concave edge ofthe bridge and an interposed edge portion of 4the diaphragm type seal toclamp and effect a seal between the latter and the base plate. Thus thebase plate and diaphragm seal comprise a bellows-type seal open to thehigh pressure gases which urge the diaphragm seal against the rubbingseal to enhance the sealing engagement therebetween and in turn urge therubbing seal against the regenerator end surface to enhance the sealingcontact therewith.

The seal is completed by a second flexible resilient diaphragm type sealinterposed between the base plate and an arcuate coaxial bafiie orplatform carried by the engine housing to partition the high and lowpressure gases from each other.

The bridge structure may comprise a bridge member of relatively rigidmaterial loosely confined between the base plate and rubbing seal andpivotally supported thereby at its opposite edges to swing its concaveedge toward and from the rubbing seal. The bridge thus provides abacking plate for the adjacent flexible diaphragm seal, so that thelatter need not be suiciently rigid to retain its form independently ofthe bridge when subject to the high pressure of the gas being sealed.

In consequence, freedom of movement between the rubbing seal and baseIplate is readily obtained and the resiliency of the diaphragm sealurging the same into sealing contact with the rubbing seal can benominal in comparison with the sealing force resulting from the gaspressure urging the rubbing seal into sealing contact With theregenerator end surface. The resultant sealing force can thus bedistributed over the inner sealing surface of the rubbing sealsubstantially as required to balance torsional forces and minimizelocalized wearing of the rubbing seal.

Another object is to provide a diaphragm type seal supported by a bridgestructure as described wherein the sealing diaphragm is arcuatecoaxially with the base plate and has a small conical angle such thatthe sealing diaphragm structure diverges from the base plate in thedirection toward the high pressure gases to receive the same betweenitself and the base plate to effect the bellowstype seal. Thediaphragmseal comprises a plane arcuate strip of thin flexible and slightlyresilient material. The ends of the strip are pulled radially inwardlyto a predetermined radius smaller than the radius of the initial planestrip to effect the conical shape and are secured to the lbase plate, asfor example by being welded thereto.

The bridge is preferably formed from a plane arcuate strip comparativelyunbendable in its radial dimension, but comparatively flexible in itscircumferential direction. Warping of the bridge in consequence of theextreme temperature conditions resulting from oper-ation of the seal isminimized by means of a plurality of circumferentially spaced slotsextending in the bridge from its convex edge. In addition the slotsfacilitate the deformation of the bridge to conform to the conical shapeof the diaphragm seal without appreciably reducing the support which thebridge offers the diaphragm seal.

Another object is to provide such a seal wherein the concave edge of thebase plate, which may be a fixed part of the engine housing if desired,is slotted radially and deformed around the adjacent concave edge of thebridge to pivotally support the latter.

Another 'object is to provide such a seal wherein the outer surface ofthe rubbing seal is offset inwardly along an arcuate shoulder extendingsubstantially the length of the seal and confronting the low pressuregases, whereby l? the diaphragm type seal overlaps the shoulder andextends along the bridge to the base plate. The bridge pivotally engagesthe inwardly ofset portion of the -rubbing seal adjacent the shoulderand extends angularly away from the rubbing seal to the base plate.

Thus the force of the high pressure gas applied against the diaphragmseal in a bellows-type action urging the same towards the rubbing sealand in turn urging the rubbing seal into sealing contact with theregenerator `surface is concentrated against the rubbing seal adjacentthe shoulder. In other words, the force of the gas pressure ,exerted onthe diaphragm seal -at the low pressure side of the shoulder is appliedagainst the bridge and thus against the line of pivotal Contact betweenthe bridge and rubbing seal adjacent the shoulder. By suitablypredetermining the location of the shoulder and the locati-on of pivotalsupport for the bridge aiforded by the base plate, both the magnitudeand the distribution of the gas pressure force against the outer side ofthe rubbing seal can be predetermined.

Other objects are to provide such a seal which bounds a sector of aregenerator surface by means of the arcuate seal described 'and asimilar but straight seal comprising fa ldiametrical or radial boundaryfor the sector, and to provide an auxiliary spring means between thebase plate and a diaphragm seal to urge the latter into sealing contactwith the rubbing seal when the gas pressure differential across the sealis low.

Other objects of this invention will appear in the following descriptionand appended claims, reference being had to the accompanying drawingsforming `a part of this specification wherein like reference charactersdesignate corresponding parts in the several views.

FIGURE 1 is a fragmentary schematic view through a gas turbine lengineembodying the present invention, taken longitudinally of the rotor axis.

FIGURE 2 is a plan View of a regenerator seal embodying the presentinvention taken in the direction of the arrows substantially Ialong theline 2-2 of FIGURE 1, portions being broken away to illustrate detailsof construction.

FIGURE 3 is a fragmentary enlarged 'sectional view taken in thedirection of the arrows substantially lalong the line 3-3 of FIGURE 2.

FIGURE 4 is a fragmentary enlarged sectional view taken in the directionof the arrows substantially along the line 4-4 of FIGURE 2. v

FIGURE 4a is a fragmentary enlarged sectional view taken in thedirection of the arrows substantially -along the line 4a-4a of FIGURE 2.

FIGURE 5 is `a fragmentary enlarged sectional view taken in thedirection of the arrows substantially along the line 5-5 of FIGURE 2.

FIGURE 6 is a fragmentary bottom view of the lower portion of the sealillustrated in FIGURE 2.

FIGURE 7 is a fragmentary enlarged elevational view of a portion of thebase plate prior t-o its assembly with the bridge structure.

FIGURE 8 is -a fragmentary elevational view taken in the direction ofthe arrows substantially along the line 8-8 of FIGURE 7.

FIGURES 9, 10 and 11 are views similar to FIG- URE 3, showing differentmodifications of the invention.

FIGURES 12, 13 and 14 are views similar to FIG- URE 4, showing differentmodifications of the invention.

FIGURE is a schematic sectional view along the diameter of theregenerator parallel to the cross arm seal, illustrating one effect ofregenerator warping.

It is to be understood that the invention is not limited in itsapplication to the details of construction and arrangement of partsillustrated in the accompanying drawings, since the invention is capableof other embodiments and of being practiced or carried out in variousWays. lalso it is to be understood that the phraseology or terminologyemployed herein is for the purpose of description and not of limitation.

Referring to the drawings, a particular embodiment of the presentinvention is illustrated by way of example in an automotive gas turbineengine comprising an engine housing 10 supporting a rotor shaft 11having a rst stage turbine -rotor 12 secured to one end thereof and arotary compressor 13 secured to its opposite end, FIG- URE 1. Thehousing v10 also supports a second stage turbine rotor 14 secured to ashaft 15 to rotate the latter and supply motive power for the vehicle.Upon rotation of the rotor 12 as described below, the compressor 13 isoperated to draw in combustion supporting air through compressor inlet16, whereby the compressor blades 17 compress and discharge the air viaa spiral diffuser 18 to an annular Kregenerator chamber 19.

The chamber 19 `contains a disk type regenerator 20 having planeparallel upper and lower axial endfaces and also having a hub 21 mountedfor rotation about the axis of a central shaft 24 by means of a graphitebearing 22 formed to provide a spherical socket confining a ball 23slidable axially along shaft 24. The latter is supported at its oppositeends within the housing 10. Accordingly the regenerator 20 is mountedfor moving freely along the axis of shaft 24 and in a universal pivotalmovement about the center of ball 23. The universal mounting 22-23 issuitably supported within the hub 21.

The -regenerator 20 `comprises an annular core or matrix 25 of axial gaspassages and is partitioned into two substantially semi-circular sectors26 and 27, FIG- URE 2, by means of superimposed semi-circular orD-shaped upper and lower seals 28 and 29 and a C-shaped seal 30. Theseals 28 and 29 may be mirror images of each other and define the sector26 for passage of high temperature and low pressure gases. The seal 30cooperates with seal 29 to define the sector 27 for comparatively coolhigh pressure gases.

The incoming air within the regenerator chamber 19 will be atapproximately the coolest temperature and highest pressure in the systemand bathes the periphery of the regenerator 20 in the cool air toprotect and facilitate operation of the regenerator drive mechanismincluding ring gear 25a secured to the periphery of regenerator 20.

The high pressure air from chamber 19 ilows into the space under thedome 31 overlying sector 27, whereupon the air is conducted through theaxial gas passages of sector 27 of regenerator matrix 25 into a`collecting chamber 32. During passage of the cool air or gases throughsector 27 of the regenerator matrix 25, these gases are heated by thematrix. The heated gases are then conducted from chamber 32 to acombustion chamber where fuel is added and burned. The hot combustionproducts or motive gases are then conducted to a spiral collectingchamber 33 and discharged into an annular gas passage 34 arranged toconduct the hot motive gases to the blades 35 and 36 of rotors 12 and 14to drive the same. The hot exhaust gases are then discharged to chamber37 below regenerator section 26 and thence upwardly through the axialgas passages of sector 26 of the regenerator matrix 25 to heat thesepassages.

Thereafter the comparatively cool exhaust gases are exhausted intochamber 38 and then to atmosphere. During rotation of the regenerator20, the hot gas passages of sector 26 are continually rotated to sector27 to preheat the cool incoming combustion supporting air.

In the present instance each regenerator end face is provided with acoplanar annular at rim 39 which extends radially from the matrix 25.The seals 29 and 30 comprise built-up structures including a three partrubbing seal adapted to lie flush against the lower trim 39 and coplanarregenerator end surface in uid sealing engagement therewith. Inasmuch asthe seal 28 may comprise a mirror image of seal 29, it will not bedescribed in detail. v

The rubbing seals include a low pressure and a high pressure C-shapedsealing member 40, 41 defining the sectors 26 and 27, respectively, anda diametrical or cross arm sealing member 42 spacing the members 40 and41. These members may be approximately .20 inch thick and in onepractical seal, their outer diameter is approximately 17 inches. Themembers 40 and 41 may be of thin graphite or other suitable sealingmaterial capable of withstanding the extreme temperature conditionsexisting in the regenerator and are sufficiently iiexible to conformclosely to the regenerator upon its thermal distortion during operation.

The cross arm member 42, FIGURE 2, in the prese-nt instance ispreferably formed of stainless steel because it is subjected to thehighest effective temperature in the seal and would rapidly disintegrateif made of graphite.

The ends of the substantially semi-circular ribbing seal members 40 and41 terminate in out-turned bosses 40a and 41a which snugly abut adjacentedges of the stainless steel cross arm rubbing seal member 42. Spacedapproximately 60 apart and integral with the rubbing seals 40 and 41,respectively, are a pair of triangular bosses 40e and 41C, eachtriangular boss having one edge parallel to the cross arm rubbing seal42 and having a second edge perpendicular thereto.

The sealing surface of the rubbing seals 40, 41 and 42 may be suitablygrooved in order to predetermine the gas pressure distribution thereonto effect a desired unit loading and thereby to minimize uneven wearing.For example, the inner surface of seal 40 is provided with asemi-circular groove 43 communicating with the high pressure of chamber19 via radial grooves 44. Thus the radial pressure gradient across thesealing surface or rubbing seal 40 will be considerably steeper and thetotal pressure force acting downwardly thereon will be somewhat greaterthan would otherwise be the case without the groove 43. In other words,the area of the rubbing seal 40 to the right of groove 43 in FIGURE 3will be at the uniform high pressure of chamber 19. Leftward of thegroove 43 the pressure applied against the outer surface of rubbing seal40 will decrease from a maximum at groove 43 to a minimum equal to thelow pressure within sector 26.

Coextensive with the rubbing seals 40, 41 and 42 is a comparativelythick and rigid stainless steel base plate comprising integralsemi-circular portions 45 and 45a underlying the rubbing seals 40 and41, respectively, and also including an integral diametrical cross armportion 45 -underlying the rubbing seal 42, FIGURE 7. The base plateportion 45, 45a and 45 preferably comprise a unitary stainless steelstamping approximately .04" thick, the peripheral portions 45 and 45abeing provided with a plurality of circumfere-ntially spaced slots 46extending radially inward from their exterior or convex edges. Thusmeans are provided to adapt the base plate to the extreme radialtemperature differential across its circumferential portions 45 and 45aand to reduce its thermally induced warping. Although the base plate isshown as a oating assembly between the rubbing seals and a fixed portionof the engine housing, the base plate itself may readily comprise afixed portion of the engine housing, if desired.

The concave edge of the base plate portion 45 and the contiguous edge ofthe base plate portion 45 which define the sector 26 are slotted at 47and 47 to minimize warping of the base plate and to facilitate foldingof these slotted edges at 45d and 45d tightly around a stainless steelwire 48. The latter extends completely around the sector opening 26 andcomprises an anchor portion of a oating bridge structure betweenassociated portions of the rubbing seal and base plate.

Cooperating with wire 48 to complete the bridge structure is an arcuatebridge member 49 extending along the 6 base plate portion 45 around thecircumferential portion of sector 26 and a cross arm or diametricalbridge member 49 extending along the diametric cross arm base plateportion 45'. The bridge members 49 and 49 have mitered juxtaposed ends49h and 49b to complete a two part D-shaped bridge confronting the outersides of rub-v bing seals 40 and 42 and have one edge of each pivotallyabutting wire 48 entirely around the sector 26, FIG- URE 2.

The `diameter of wire 48 is approximately two or three times thethickness of the bridge members 49 and 49 so that the slotted or groovededges 45d and'45d of the base plate wrapped around wire 48 will bespaced from the adjacent bridge portion 49 and 49 by a clearance 50. Thelatter is exaggerated in FIGURES 3 and 4 and in the usual instance, thewire 48 will be somewhat iiattened by the force applied in ben-ding theslotted base plate edge therearound. In order to provide adequaterigidity in the transverse dimension of the bridge portions 49 and 49',these are formed of stainless steel approximately .02" to .03 thick,whereas the diameter of wire 4S is approximately .05.

The outer surface of the rubbing seals 40 and 42 are recessed at 51 and51', respectively, FIGURES 3 and 4, to provide shoulders 52 and 52against which the exterior edges of the bridge members 49 and 49 areloosely seated for pivotal movement. Thus the bridge members 49 and 49are freely floating between the rubbing seals 40 and 42 an-d associatedbase plate portions 45 and 45. In operation, the gas pressure acting onthe seal as described below will urge the base plate away from thelrubbing seal and will urge the latter against the regenerator surface,thereby to eliminate the clearan-ce 50 between the bridge and slottededges 45d and 45d. The upward lgas pressure load on the bridge will thusbe transferred to the edges 45d and 45d and to the rubbing sealsadjacent the shoulders 52 and 52.

As illustrated in FIGURES 2 and 7, the opposite ends of the base platecross arm 45 are provided with integral bosses 45h which underlie thebosses 40a and 41a of the arcuate rubbing seals 40 and 41 and theassociated ends of the cross arm rubbing seal 42. In addition thecircumferential base plate portions 45 and 45' are each provided with apair of triangular bosses 45C corresponding in shape and underlying therubbing -seal bosses 40C and 41C. In order to retain the rubbing sealsand base plate Imembers together in assembled relationship, the bosses45h are each provided with a pair of lateral tabs 53 and an end tab 54which extend upwardly adjacent the rubbing seal bosses 40a and 41a andthe end of cross ar-m rubbing seal member 42. The tabs 53 are providedwith pin hol-es 60, FIGURE 8, through which extend a suitable retainingpin y60a loosely overlying the tabs 40a and 41a and the end of cross armrubbing seal 42.

The bosses 45e are similarly provided with locating tabs 56 and 57. Atleast one of each pair is bent to loosely overlie the associated rubbingseal boss 40e or 41C. Each of the base plate bosses 45b is also providedwith a locating dowel hole 58 adapted to receive a dowel pin projectingfrom the engine frame to prevent unintentional assembly of the seals 28,30 in the housing 180 out of phase.

A gas tight seal between the base plate portions 4S, 45 and theassociated rubbing seal members 40, 42 is accomplished by means of adiaphragm type seal including a two part D-shaped diaphragm seal and atwo pa-rt D-shaped diaphragm support. The diaphragm seal includes anarcuate portion V62 and a dia-metric or cross arm portion `62 extendingalong the circumferential and diametric portions, Irespectively, ofsector yopening 26. The D-shaped diaphragm support comprises acircumferential portion 63 and a diametric or cross arm portion 63extending along the circumferential and diametric porti-ons,respectively, of sector opening 26.

The interior edges of the D-shaped diaphragm support Y the conical sealshape. at 74 along its inner circumference to effect a fluid tight 63,63' overlie and are suitably secured to the associated base plateportions 45 and 45', FIGURES 2 and 3, as for rvarcuate base plateportion `45 and the welding seam 64' 'along the cross arm, base plateportion 45', FIGURES A3 and 4. In construction, the support 63, 63 iswelded at 64 and 64' to the base plate prior to folding the edges 45dand 45d'. Thereafter these edges are folded aro-und the wire 48 asillustrated. From the weld seams 64 and 64', the diaphragm support63-63' extends away from the sector opening 26 along the associatedbridge portions 49 and 49' and overlaps the corresponding shoulders 52and 52 The arcuate portion 62 of the diaphragm seal is cut from thinstainless steel sheet material to a larger radius than the finalassembled radius shown and is then distorted to a conical shape bypulling its ends I62a into the smaller radius illustrated. The interioredge of the diaphragm seal 62 is wedged tightly between the base plate45 and `diaphragm support 63 and the opposite ends 62a are welded at 65to the cross arm portion 45' of the base plate. In accordance with thiscon-struction, replacement of the diaphragm seal 62 is Ireadilyaccomplished by prying loosethe weld yseams 65 and sliding the diaphragm62- from between the `base plate 45 and support 63.

The dia-metric or cross arm diaphragm seal 62' is similarly wedgedbetween the portions 63 and 45 of the diaphragm support and base plate,respectively. It is not welded in position, so is readily replaceable.The diaphragms 62, 62' extend from the sector opening 26 so as tooverlap the exterior edges of diaphragm support 63, 63' and engage thejuxtaposed outer surfaces of the rubbing seal portions 40 and 42 tocomplete a fluid tight seal therewith entirely around the sect-or 26.

Around the circumferential portion of sector opening 27 extends aconical diaphragm -seal 66 similar to the seal 62 having opposite ends66a underlying the ends of seal 62, FIGURE 2. The interior edge of seal66 is secured to the base plate portion 45a by an arcuate weld seam `67to provide a fluid tight seam entirely around the circumference of thesector opening 27.

In order to enable the arcuate bridge portion 49 to conform to theconical shape of diaphragm seal `62, it is provided with a plurality ofcircumferentially spaced slots 68 extending radially therein `fro-m itsedge adjacent shoulder 52. Similar but less closely spaced slots 68' areprovided in the cross arm bridge portion `49' to enable the latter toconform more closely to the contour of rubbing seal 42 upon deformationthereof in accordance with thermal warping of regenerator 20. Inasmuchas the cr-oss arm bridge member 49' is somewhat wider than is thearcuate portion `49, the bridge portion `49' is preferably somewhatthicker and is provided with a cham-fered edge 49a' at its edge abuttingwire 48, FIGURE 4.

The arcuate bridge portion 49 is also provided with several notches 70to accommodate bent-over tabs 71 of the diaphragm support 63 which holdthe bridge adjacent the wire 48 to facilitate handling of the seal priorto its assembly with the rubbing seal 49. Similarly the diaphragmsupport 63' provides several tabs 73 bent over bridge 49' to hold thelatter adjacent the wire 48.

Similarly to the sealing diaphragm 62 around the circumference ofsector'26 on the regenerator side of base plate 45, an arcuate conicalstainless steel di-aphragm seal 73 is provided on thefopposite side ofthe base plate 45, FIGURE 6. The ends 73a of the diaphragm seal 73 arepulled'radially inwardly to the desired diameter to effect The diaphragm73 is then welded seam entirely around the circumference of sector 27and also extending across the opposite ends of the cross arm portion 45'of the base plate.

Around the circumference of the sector 27 extends another conical seal75 similar to the seal 73. The opposite ends 75a of the seal 75 overlapthe ends 73. The interior edge of seal 75 is welded at 76 to the baseplate 45a to effect a continuous seal around the circumference of thesector 27, the welded seams 74 and '76 comprising continuations of eachother. Underlying the base platecross arm 45' is a C-shaped diaphragmseal 77, which similarly to the seals 73 and 75 is pulled radiallyinwardly at its opposite ends to effect the desired conical shape. Theopposite ends 77a of the seal '77 overlap end portions of the seal 73,the seal 77 being secured to the base plate portions 45 and 45 at a weldseam 78 which merges at its opposite ends with weld seam 74 and extendsalong the edge of the diaphragm seal 77 proximate the sector opening 26.

The diaphragm seals 73 and 75 overlie and engage an annular rigidplatform '79 of the engine frame to effect a bellows type fluid sealtherewith open to the high pressure air of chamber i9. The cross armseal 77 overlies and engages a cross arm platform portion S0 comprisinga coplanar diameter of the annular platform 79, thereby to effect abellows type seal with the platform 80 open to the comparatively highpressure gases in sector 27. All of the seals 62, 62', 66, 73, 75 and 77`and supports 63, 63' are formed from thin flexible resilient stainlesssteel sheet stock, the seals being approximately .002" to .004" thickand the supports 63, 63 being slightly thicker to afford suicientrigidity to prevent blow out of the seals 62, 62' at the regions of theshoulders 52, 52'.

By the construction described, the seals 62 and 62' cooperate with theassociated base plate portions 45 and 45' to complete bellows-type sealsopening to receive the high pressure gases from chamber 19 and sector27, whereby the diaphragm seals 62 and 62' are urged against the outersurfaces of the rubbing seals 40 and 42 into fluid sealing engagementtherewith. The bridge portions 49 and 49' freely pivotal at theirinterior and exterior edges with respect to the sector opening 26 enablethe rubbing seals 40, 42 to move freely as required in order to conformto the regenerator in the sealing operation in accordance with itsthermal distortion. Around the sector opening 27, the diaphragm seal 66cooperates with the base plate portion 45a to complete a diaphragm sealopen to the high pressure gases in chamber 19 to urge seal 66 snuglyinto sealing engagement with adjacent surfaces of the rubbing seal 41.In the same action, the gas pressures acting on diaphragm seals 62, 62and 66 urge the rubbing seals 40, 41 and 42 into sealing engagement withthe regenerator 20.

Similarly the diaphragm seals 73 and 75 cooperate with adjacent portionsof the base plate opposite the rubbing seals to complete bellows-typeseals open to the high pressure gases of chamber 19, so that diaphragmseals 73 and 75 are urged by fluid pressure into sealing engagement withplatform 79. In a like manner seal 77 completes a bellows-type seal withbase plate 45', the seal being open to the comparatively high pressuregases of chamber 27 to urge diaphragm seal 77 into sealing engagementwith cross arm platform S0. In the above reg-ard, the area at the innersurface of the lbase plate 457 45' (i.e., at the upper side thereof inFIGURES 3 and 4) exposed to the high pressure gases is greater than thecorresponding area at the opposite side of the base plate. Inconsequence the base plate and seals 73, 75, 77 will be heldsubstantially flat -against the platform 79, 80.

By virtue of the diaphragm supports 63 and 63', the gap between thebridge portions 49 and 49 and associated rubbing seals 40 and 42 issuitably bridged to prevent damage to the thinner diaphragm seals 62 and62'. Accordingly the diaphragm supports 63 and 63' enable the use of athinner diaphragm seal than would otherwise be possible, achieving amore eicient seal capable of operating at high pressure. Duringoperation of the regenerator 20, the comparatively cool gas flowingdownwardly through chamber and rotors 12, 14.

sector 27 and being heated in its travel through the regenerator tendsto m-aintain the upper surface of the regenerator cool with respect tothe lower surface. Similarly the hot exhaust gases flowing upwardthrough the sector 26 and being cooled in their travel through theregenerator tend to maintain the lower portion of the regenerator 20hotter than the upper portion. In consequence the entire upper portionsof the regenerator 20 operate -at 4an appreciably lower temperature thanthe lower portions thereof in FIGURE l, so that the regenerator tends tobow or dish as illustrated in FIGURE l5, wherein the bowing isexaggerated for the sake of illustration.

During operation, the high pressure gases acting on the seal urge therubbing seals 40-42 closely against the regenerator surface so as toconform closely thereto during its thermal distortion. When the engineis not in operation and the regenerator 20 cools, the l-atter and theseals will tend to return to their undeformed shapes. In consequence ofyresidual warping of the regenerator and seals, these members may nolonger conform closely to each other, particularly at the region of thecross arm seal. Without some provision to the contrary, gaps amountingto several thousandths of an inch frequently exist between the rubbingseal 42 Vand the confronting plane face of the regenerator matrix. Whenan attempt is then made to start the engine, lthe cross arm portion ofthe seal will leak and permit an appreciable proportion of the inlet orcombustion supporting air to ilow directly from section 27 to sector 26and bypass the combustion This results because the seal is not subjectto a sufficiently high pressure differential to hold the rubbing seal 42tightly against the regenerator. A large starting motor will thus berequired to compensate for the leakage across the cross arm seal.

In order to facilitate starting of the engine with a starting motor ofminimum size, a supplementary leaf spring 82 is provided to extendlengthwise of the cross arm rubbing seal 42. The leaf spring 82 is bowedtransversely of the cross arm seal 42, FIGURE 4, and is preferablyVarranged -to underlie the sealing diaphragm 62 along a substantiallyline contact at the high pressure side of shoulder 52 so as to urge seal62 into its sealing engagement with the rubbing seal 42 during startingof the engine when the gas pressure is low. The spring 82 also urges theflexible rubbing seal 42 into sealing engagement with the confrontingface of the regenerator 2l).

By virtue of the leaf spring 82, the cross arm rubbing seal 42 will beurged into sealing engagement with the regenerator to prevent gas llowdirectly from sector 27 to sector 26. The leaf spring 82 may be employedat the upper regenerator seal 28 and around the peripheral portions ofthe seals 29 and 30 but is less essential at these regions because thetendency of the regenerator matrix to pull away from the associatedseals at these locations is less pronounced.

As indicated in FIGURE 4, the right edge of the leaf spring 82 fitssnugly under the diaphragm seal 62. Leftward shifting of the leaf spring82 in FIGURE 4 is prevented by a pair of tabs 83 integral with the crossarm base plate 45 and bent upwardly from its left edge, FI G- URES 2 and7. As indicated in FIGURE 4a an annular sealing disk 84 of thinresilient material similar to the material of the `diaphragm seal 62 islocated around the shaft 24 between the leaf spring 82 and diaphragmseal 62. An inner annular projection 34a of the disk 8-4 ts tightlyaround shaft 24 in sealing engagement therewith. The high pressure gasesbetween the base plate 45 and disk 84 substantially flattens the latteragainst the diaphragm 62' to effect a seal to prevent leakage of gasesthrough the necessarily large clearance hole in the seal 62 for shaft24. The flexibility of the seal enabled by the bridge 49, 49' lendsitself yto numerous modifications, some of which are illustrated by wayof example in FIG- URES 9 through 14.

In FIGURE 9 the diaphragm support 63 is omitted and the `diaphragm seal62 is suitably confined between the wire 48 and base plate 4S to effecta bellows-type seal between the latter and diaphragm 62. The seal may'be effected by welding the diaphragm 62 to the base plate 45 along aseam 64a comparable to the seam 64 or 64. This structure, like thestructu-re illustrated in FIGURE `3, may be employed either with theperipheral portions of the sectors 26 `and 27 or the cross arm portionthereof. The elimination of diaphragm support 63, as in FIG- URE 9, willsimplify the sealing structure but will require a heavier and moreinflexible sealing diaphragm 62.

In FIGURE l0 the wire 48 is eliminated and the seal between thediaphragm 62 and base plate 45 is accomplished by the welding seam 64a.

In FIGURE ll, the wire 48 is eliminated and the low pressure edge of thebridge 49 is curved in the loop 49h to interfit pivotally within theedgeloop 45d of the base plate 45.

The Structures of FIGURES 9, l0 and 1l may be ernployed either at theperipheral portions of the sectors to be sealed or at the base plateportions thereof and may be employed either with or without a leafspring 82 to enhance or to supplant the resiliency of the sealingdiaphragm 62 as illustrated in FIGURES 12, 13 and 14. In other respects,the seals of FIGURES 9-14 are the same as described above with respectto the preceding figures, especially FIGURES 3 and 4.

' We claim:

1. In a seal for the regenerator of a gas turbine engine, rubbing meanshaving an inner `sealing surface adapted t-o engage a mating surface ofsaid regenerator to define a seal between high and low pressure gases,base means confronting an outer side of said rubbing means opposite saidsealing surface and being movable toward and from the same, diaphragmsealing means interposed between said base means and rubbing means andengaging said rubbing means in fluid sealing relationship, said sealingrneans extending from said rubbing means in the direction toward the lowpressure gases, bridge means having one edge pivotally engaging saidrubbing means at a location overlapped by said sealing means, saidbridge means extending in juxtaposition with said sealing means fromsaid one edge to a swinging edge to comprise a backing for said sealingmeans, said sealing means having a portion welded to said base means toeffect a fluid tight seam extending longitudinally of said seal, thelatter portions and juxtaposed portion of the base means being formedaround said swinging edge of said bridge means, said base means andsealing means comprising a bellows type seal open to said high pressuregases to enhance said fluid sealing relationship, -and a leaf springinterposed under tension between said base rneans and sealing means andengaging the latter longitudinally of said seal to maintain said fluidsealing relationship between said sealing means and rubbing means.

2. In the combination according to claim 1, said bridge means comprisinga backing plate and a wire, said one edge of said bridge means being oneedge of said backing plate, said backing plate also having a swingingedge, said Wire extending longitudinally of said seal along the swingingedge of said backing plate and comprising the swinging edge of saidbridge means.

3. In a seal for the regenerator of a gas turbine engine, rubbing meanshaving an inner sealing surface adapted to engage a mating surface ofsaid regenerator to define a seal between high and low pressure gases,base means confronting an outer side of said rubbing means opposite saidsealing surface and being movable toward and from the same, bridge meansincluding a backing plate having one edge pivotally engaging said outerside of said rubbing means and also including a wire extendinglongitudinally of said seal, said backing plate extending in thedirection toward lthe low pressure gases and terminating in an edgeengaging said wire to space the same from said one edge,

resilient sealing means having a portion clamped between said wire and aportion of said base means formed around said wire to effect a fluidseal between said sealing and base means, said resilient sealing meanslapping the engagement between said bridge means and rubbing means andengaging the latters outer side in fluid sealing relationship, said basemeans and resilient sealing means comprising a bellows type seal open tosaid high pressure gases to enhance said fluid sealing relationship, andmeans urging said rubbing means into sealing engagement with saidregenerator during starting of said engine comprising a leaf springextending longitudinally of said seal and interposed under tensionbetween said base means and sealing means, said leaf spring being bowedtransversely of the length of said seal and engaging said sealing meansalong a line extending longitudinally of said seal.

YL In combination with a disc type regenerator for a gas turbine engine,a resiliently yieldable cross arm extending across one face of saidregenerator and being flexible to conform to said face upon thermaldistortion of said regenerator, thereby to define a seal between highand low pressure gases, said cross arm comprising flexible rubbing meanshaving an inner sealing surface adapted to engage a mating surface ofsaid regenerator, a flexible base member confronting an outer side ofsaid rubbing means opposite said sealing surface and being movabletoward and from the same, a flexible sealing diaphragm interposedbetween said base member and rubbing means and engaging the latter influid sealing relationship, said diaphragm extending from said rubbingmeans in the direction toward the low pressure gases, a flexible bridgecomprising a wire extending longitudinally of said seal and a backingplate having `one edge pivotally engaging said rubbing means at alocation overlapped by said diaphragm, said backing plate extending injuxtaposition with said diaphragm in said direction from said one edgeto said wire to comprise a backing for said diaphragm and to space saidwire from said one edge, said diaphragm and base member being formedaround said wire to clamp said diaphragm between said wire and basemember, said base member and diaphragm comprising a bellows type sealopen to said high pressure gases to enhance said fluid sealingrelationship, and means urging said rubbing means of said cross arm intosealing engagement with said regenerator during starting of said enginecomprising a leaf spring extending longitudinally of said cross arm andinterposed under tension between said base member and diaphragm, saidleaf spring being bowed transversely of the length of said arm andengaging said diaphragm along a line extending longitudinally of saidseal.

5. In the combination according to claim 4, the outer side of saidrubbing means having an inwardly offset prtion providing a shoulderconfronting said low pressure gases and extending longitudinally of saidseal at a location overlapped by said sealing diaphragm, said one edgeof said backing plate pivotally engaging said offset portion adjacentsaid shoulder, and the engagement between said diaphragm and rubbingmeans terminating adjacent said shoulder.

6. In the combination according to claim 4, said diaphragm having aportion welded to said base member to complete a fluid tight seamextending longitudinally of said seal, said basel member and weldedportion of said diaphragm being formed closely around said wire.

7. In the combination according to claim 6, the outer side of saidrubbing means having an inwardly offset portion providing a shoulderconfronting said lowl pressure gases and extending longitudinally -ofsaid seal at a location overlapped by said sealing diaphragm, said oneedge of said backing plate pivotally engaging said offset portionadjacent said shoulder, and the engagement between said diaphragm andrubbing means terminating against said shoulder.

`8. In combination with a disc type regenerator for a gas turbineengine, a resiliently yieldable cross arm extending across one face ofsaid regenerator and being lflexible to conform to said face uponthermal distortion of said regenerator, thereby Ito define a sealbetween high and low pressure gases, said cross arm comprising flexiblerubbing means having an inner sealing surface adapted to engage a matingsurface of said regenerator, a flexible base member confronting an outerside of said rubbing `means opposite said sealing surface and beingmovable toward and from the same, a flexible sealing diaphragminterposed between said base member and rubbing means and engaging thelatter in fluid sealing relationship, said diaphragm extending from saidrubbing means in the direction toward the low pressure gases, a flexiblediaphragm support interposed between said diaphragm and rubbing meansand terminating at one edge overlapped by said diaphragm, said supportextending from said one edge thereof in said direction in juxtapositionwith said diaphragm to support the latter, a flexible bridge comprisinga wire extending longitudinally of said seal and a backing plate havingone edge pivotally engaging said rubbing means at a location overlapped'by said support, said backing plate extending in juxtaposition with saidsupport in said direction from said one edge to said wire to comprise abacking for said support and to space said wire from said one edge, saidsupport and base member being formed around said wire to clamp saidsupport between said wire and base member to complete a seal with thelatter, said base member and diaphrgam comprising a bellows type sealopen to said high pressure gases to enhance said fluid sealingrelationship, and means urging said r-ubbing means of said cross arminto sealing engagement with said regenerator during starting of saidengine comprising a leaf spring extending longitudinally of said crossarm and interposed under tension between said base member and diaphragm,said leaf spring being bowed transversely of the length of said arm andengaging said diaphragm along a line extending longitudinally of saidsea 9. In the combination according to claim 8, the outer side of saidrubbing means having an inwardly offset portion providing a shoulderconfronting said low pressure gases and extending longitudinally of saidseal at a location overlapped by said support, said one edge of saidbacking plate pivotally engaging said offset portion adjacent saidshoulder, and the engagement between said support and rubbing meansterminating adjacent said shoulder.

10. In the combination according to claim 8, said support having aportion welded to said base member to complete a fluid tight seamextending longitudinally of said seal, said base member and weldedportion of said support being formed closely around said wire.

11. In the combination according to claim 10, the outer side of saidrubbing means having an inwardly offset portion providing a shoulderconfronting said low pressure gases and extending longitudinally of saidseal at a location overlapped by said support, said one edge of saidAbacking plate pivotally engaging said offset portion adjacent saidshoulder, and the engagement between said support and rubbing meansterminating adjacent said shoulder.

12. In combination with a disc type regenerator for a gas turbineengine, a resiliently yieldable cross arm extending across one face ofsaid regenerator and being flexible to conform to said face upon thermaldistortion of said regenerator, thereby to define a seal between highand low pressure gases, said cross arm comprising flexible rubbing meanshaving an inner sealing surface adapted to engage a mating surface ofsaid regenerator, a flexible `base member confronting an outer side ofsaid rubbing means opposite said sealing surface and being movabletoward -and from the same, a flexible sealing diaphragm interposedbetween said base member and rubbing means and engaging the latter influid sealing relationship, said diaphragm extending from said rubbingmeans in the direction toward the lo-w pressure gases, a flexible bridgeextending longitudinally of said seal and having one edge pivotallyengaging said rubbing means at a location overlapped by said diaphragm,said bridge extending in juxtaposition with said diaphragm in saiddirection from said one edge to a second edge parallel to said seal,said diaphragm and base member being formed around said second edge toclamp said diaphragm between said second edge and base member to effecta seal between said base member and diaphragm, said base member anddiaphragm comprising a bellows type seal open to said high pressuregases to enhance said fluid sealing relationship, and means urging saidrubbing means of said cross arm into sealing engagement with saidregenerator during starting of said engine comprising a leaf springextending longitudinally of said cross arm and interposed under tensionbetween said base member and diaphragm, said leaf spring being bowedtransversely of the length of said arm and engaging said diaphragm alonga line extending longitudinally of said seal.

13. In the combination according to claim 12, the outer side of saidrubbing means having an inwardly offset portion providing a shoulderconfronting said low pressure gases and extending longitudinally of saidseal at a location overlapped by said sealing diaphragm, said one edgeof said backingplate pivotally engaging said offset portion adjacentsaid shoulder, and the engagement between said diaphragm and rubbingmeans terminating adjacent said shoulder.

14. In the combination according to claim 12, said diaphragm having aportion welded to said base member to complete a fluid tight seamextending longitudinally of said seal, said base member and weldedportion of said diaphragm being formed closely around said wire.

15. In the combination according to claim 14, the outer side of saidrubbing means having an inwardly offset portion providing a shoulderconfronting said low pressure gases and extending longitudinally of saidseal at a location overlapped by said sealing diaphragm, said one edgeof said backing plate pivotally engaging said offset portion adjacentsaid shoulder, and the engagement between said diaphragm and rubbingmeans terminating adjacent said shoulder.

1-6. In combination with a disc type regenerator for a gas turbineengine, a resiliently yieldable cross arm extending across one face ofsaid regenerator and being flexible to conform to said face upon thermaldistortion of said regenerator, thereby to define a seal between highand low pressure gases, said cross arm comprising flexible rubbing meanshaving an inner sealing surface adapted to engage a mating surface ofsaid regenerator, a flexible base member confronting an outer side ofsaid rubbing means opposite said sealing surface and being movabletoward and from the same, a flexible sealing diaphragm interposedbetween said -base mem-ber and rubbing means and engaging the latter influid sealing relationship, said diaphragm extending from said rubbingmeans in the direction toward the low pressure gases, a flexiblediaphragm support interposed between said diaphragm and rubbing meansand terminating at one edge overlapped by said diaphragm, said supportextending from said one edge thereof in said direction in juxtapositionWith said diaphragm to support the latter, a flexible bridge extendinglongitudinally of said seal and having one edge pivotally engaging saidrubbing means at a location overlapped by said support, said bridgecomprising a backing for said support and extending in juxtapositiontherewith in said direction from said one edge thereof to a second edgeparallel to said seal, said diaphragm and base member being formedaround said second edge to clamp said support between said second edgeand base member to effect a seal between said support and base member,said base member and diaphragrn comprising a bellows type seal open tosaid high pressure gases to enhance said fluid sealing relationship,

and means urging said rubbing means of said cross arm into sealingengagement with said regenerator during starting of said enginecomprising a leaf spring extending longitudinally of said cross arm andinterposed under tension between said base member and diaphragm, saidleaf spring being bowed transversely of the length of said arm andengaging said diaphragm along a line extending longitudinally of saidseal.

17. In the combination according to claim 16, the outer side of saidrubbing means having an inwardly offset portion providing a shoulderconfronting said low pressure gases and extending longitudinally of saidseal at a location overlapped by said support, said one edge of saidbridge pivotally engaging said offset portion adjacent said shoulder,and the engagement between said support and rubbing means terminatingadjacent said shoulder.

18. Invthe combination according to claim 16, said support having aportion welded to said base member to complete a fluid tight seamextending longitudinally of said seal, said base member and weldedportion of said support being formed closely around said second edge ofsaid bridge.

19. In the combination according to claim 18, the outer side of saidrubbing means having an inwardly offset portion providing a shoulderconfronting said low pressure gases and extending longitudinally of saidseal at a location overlapped by said support, said one edge of saidbridge pivotally engaging said offset portion adjacent said shoulder,and the engagement between said support and rubbing means terminatingadjacent said shoulder.

20. In a seal for the regenerator of a gas turbine engine, rubbing meanshaving an inner sealing surface adapted to engage `a mating surface ofsaid regenerator to define a seal between high and low Ipressure gases,base means confronting an outer side of said rubbing means opposite saidsealing surface and being movable toward and from the same, diaphragmsealing means interposed between said base means and rubbing means andengaging said rubbing means in fluid sealing relationship, said sealingmeans extending from said rubbing means in the direction toward the lowpressure gases, bridge means having one edge pivotally engaging saidrubbing means at a location overlapped by said sealing means, saidbridge means extending in juxtaposition with said sealing means fromsaid one edge to a swinging edge to comprise a backing for said sealingmeans, said sealing means engaging said base means and swinging edge ofsaid bridge means to effect a fluid seal therebetween, and a leaf springinterposed under tension between said base means and sealing means andengaging the latter longitudinally of said seal to maintain said fluidsealing relationship between said sealing means and rubbing means, saidbase means and sealing means comprising a bellows type seal open to saidhigh pressure gases to enhance said fluid sealing relationship.

21. In a seal for the regenerator of a gas turbine engine, rubbing meanshaving an inner sealing surface adapted to engage a mating surface ofsaid regenerator to define a seal between high and low pressure gases,base means confronting an outer side of said rubbing means opposite saidsealing surface and being movable toward and lfrom the same, the outerside of said rubbing means having an inwardly offset portion providing ashoulder confronting said low pressure gases and extendinglongitudinally of said seal, diaphragm sealing means interposed betweensaid base means and rubbing means and engaging said rubbing means influid sealing relationship, said sealing means extending from saidrubbing means in the direction toward the low pressure gases, bridgemeans having one edge pivotally engaging said offset portion of saidrubbing means at a location adjacent said shoulder and overlapped bysaid sealing means, said bridge means extending in juxtaposition withsaid sealing means from said one edge to a swinging edge to com- 15prise a backing for said 'sealing means, the engagement between saidsealing means and rubbing means terminating adjacent said shoulder, saidsealing means also engagingV said base means and the swinging edge ofsaid bridge means to effect a iluid seal therebetween, and a leaf springinterposed under tension between said base means and sealing means andengaging the latter longitudinally of said seal at the low pressure sideof said shoulder to maintain said uid sealing relationship between saidsealing means and rubbing means, said base means and sea-ling ReferencesCited by the Examiner UNITED STATES PATENTS 2,880,972 4/1959 Williams165-9 3,185,208 5/1965 Chute 165-9 3,204,969 9/1965 Williams 165-9 XROBERT A. OLEARY, Primary Examiner.

10 A. W. DAVIS, Assistant Examiner'.

1. IN A SEAL FOR THE REGENERATOR OF A GAS TURBINE ENGINE, RUBBING MEANSHAVING AN INNER SEALING SURFACE ADAPTED TO ENGAGE A MATING SURFACE OFSAID REGENERATOR TO DEFINE A SEAL BETWEEN HIGH AND LOW PRESSURE GASES,BASE MEANS CONFRONTING AN OUTER SIDE OF SAID RUBBING MEANS OPPOSITE SAIDSEALING SURFACE AND BEING MOVABLE TOWARD AND FROM THE SAME, DIAPHRAGMSEALING MEANS INTERPOSED BETWEEN SAID BASE MEANS AND RUBBING MEANS ANDENGAGING SAID RUBBING MEANS IN FLUID SEALING RELATIONSHIP, SAID SEALINGMEANS EXTENDING FROM SAID RUBBING MEANS IN THE DIRECTION TOWARD THE LOWPRESSURE GASES, BRIDGE MEANS HAVING ONE EDGE PIVOTALLY ENGAGING SAIDRUBBING MEANS AT A LOCATION OVERLAPPED BY SAID SEALING MEANS, SAIDBRIDGE MEANS EXTENDING IN JUXTAPOSITION WITH SAID SEALING MEANS FROMSAID ONE EDGE TO A SWINGING EDGE TO COMPRISE A BACKING FOR SAID SEALINGMEANS, SAID SEALING MEANS HAVING A PORTION WELDED TO SAID BASE MEANS TOEFFECT A FLUID TIGHT SEAM EXTENDING LONGITUDINALLY OF SAID SEAL, THELATTER PORTIONS AND